The 1790 act simply required a child born outside the U.S. to have one citizen parent. Additionally a child could not be a natural born citizen if their “fathers have never been resident in the United States.” Ted Cruz’s father had previously been a legal resident of the United States and his mother was a U.S. citizen. Thus according to the first Congress he was a natural born citizen.
Your mistake is referring to an act of Congress for help in determining the definition of “natural born.” I’m sorry, can Congress amend the Constitution?